Lead is a metal found naturally in the environment, as well as in manufactured products. The major sources of lead emissions have historically been motor vehicles and industrial sources. As a result of the permanent phase-out of leaded gasoline and other national and state regulations, airborne lead concentrations have decreased in the U.S. by 94 percent between 1980 and 2007. Industrial processes are now the major source of airborne lead emissions, including lead smelters, waste incinerators, utilities, and lead-acid battery manufacturers. 

Health Effects

While lead emissions have been greatly reduced nationwide, scientific evidence about the impact of lead on health has expanded dramatically since the U.S. Environmental Protection Agency or EPA first issued a lead standard in 1978. Lead can be emitted into the air in the form of particles small enough to stay suspended in the air. Lead emitted into the air can be inhaled directly or ingested after it settles onto surfaces or soils. Once in the body, lead is rapidly absorbed into the bloodstream and accumulates in the bones. Lead exposure is associated with several health effects that have an adverse impact on the cardiovascular system, central nervous system, kidneys, and immune system. 

Children are more susceptible to the damaging effects of airborne lead than adults because they breathe in more air per minute, typically spend more time outdoors, and exhibit greater hand-to-mouth activity than adults. Children are also more vulnerable to the health effects of lead because their minds and bodies are developing rapidly. 

Missouri’s Lead Legacy

Missouri’s long history of lead mining and processing can be traced back to French explorers in the early 1700s. Missouri continues to be a world leader in lead mining and processing. Historical lead mining areas include the Old Lead Belt around Park Hills in St. Francois County and the Tri-State Lead area around Joplin in Jasper and Newton Counties. Lead continues to be mined from the New Lead Belt, or Viburnum Trend, located in Iron and Reynolds Counties. The Viburnum Trend is the largest lead mining district in the world.  Herculaneum, located in Jefferson County, was the site of the nation’s last primary lead smelter prior to the site ceasing primary lead smelting operations in early 2014. Glover and Buick, both located in Iron County, also had primary lead smelting operations at one time. The smelter in Glover is no longer operating and the Buick facility is now used for secondary smelting, where lead is recycled from lead-acid batteries, picture tubes, spent ammunition, and other lead-bearing material. 

Lead Standard Revision

On October 15, 2008, the EPA promulgated a revised National Ambient Air Quality Standard or NAAQS for lead. The revision strengthened the 1978 standard tenfold, decreasing the standard for airborne lead from 1.5 to 0.15 micrograms per cubic meter. The significantly lower standard has the potential to affect more areas of the state, which will be determined using data from the Missouri Department of Natural Resource’s expanded monitoring network that became operational in January 2010. 

Boundary Recommendations

The EPA requires each state to determine which areas in the state will not meet the 2008 NAAQS for lead, known as nonattainment areas. Herculaneum is the only nonattainment area in Missouri under the 1978 NAAQS. Missouri also has two maintenance areas located near Buick and Glover.  Doe Run operates the secondary smelter near Buick and owns the inactive primary smelter near Glover. The Buick and Herculaneum areas will clearly have difficulty meeting the new standard. The department presented a draft nonattainment recommendation at a public information session on Sept. 16, 2009, and at a formal public hearing on Oct. 29, 2009. On Dec. 3, 2009, the Missouri Air Conservation Commission adopted the department’s final recommendations. The recommendations included keeping the Herculaneum nonattainment area in Jefferson County as the Herculaneum city limits and adding a nonattainment area around the Buick smelter and mine in Dent, Iron, and Reynolds Counties. Additionally, the State recommended certain county portions around each of these two nonattainment areas as unclassifiable until monitoring data was available from the new samplers that were in place by January 1, 2010. The recommendation also included unclassifiable areas in the Old Lead Belt (St. Francois County) and the Tri-State area (Jasper and Newton Counties). The EPA concurred with our recommendations in its first round final determinations published on November 16, 2010. In a letter to the Governor dated June 14, 2011, EPA outlined its preliminary decision for the second round of designations. EPA proposed to keep the nonattainment area designations unchanged from the first round. No monitoring data from any of the four newly-monitored areas (portions of five counties) indicated a violation of the NAAQS. The EPA gave the State until August 15, 2011, to respond with any comments prior to finalizing this second round no later than October 14, 2011. On July 13, 2011, Missouri responded in agreement with these recommendations. More information on nonattainment boundary recommendations can be found on the National Ambient Air Quality Standard Area Boundary Designations page.

State Implementation Plans

After the nonattainment area designations are finalized, states are required by the federal Clean Air Act or CAA to develop and maintain a state implementation plan or SIP that provides the state's air pollution control strategy for meeting the requirements of the CAA. The SIP is submitted to the EPA and includes the specific state rules and state plans that make up the state's air pollution control strategies.  In 2013, Missouri submitted attainment demonstration SIPs to EPA for both the Herculaneum and Buick nonattainment areas.

State Implementation Plans for Lead

Lead State Implementation Plan

Monitoring Information

Herculaneum Area Air Monitoring Sites
Viburnum Trend and Old Lead Belt Monitoring Sites
Tri-State Area Monitoring Sites
Preliminary 3-month Rolling Average Data

Related Links